In FY 2015, we continued our efforts to understand the impact that phenol-soluble modulins have on biofilm development. We have completed our set of isogenic deletion mutants in S. epidermidis psm loci to investigate the role all PSMs play in S. epidermidis biofilm development and dissemination from device-related infection in vivo and are analyzing the impact of all PSMs on S. epidermidis biofilm formation. Furthermore, we continued collaboration with Dr. Hickok (Jefferson University) on characterizing biofilm formation as a phenomenon underlying difficult-to-treat joint infections.